In the field of computer networks, ICMP Echo, more familiar as PING, is a tool for measuring the delay of an Internet connection between a client and a target host (ICMP=Internet Control Message Protocol; PING=Packet Internet Groper). The quality of data communication is further checked by test messages resembling the real data stream, and evaluating the delay of individual messages, the transmission failures, re-transmissions and uncorrected errors.
With the growing use of packet based telecommunication channels for highly delay-sensitive applications such as telephony or video conferencing, there is also a need to monitor the quality of a packetised real-time connection. Contrary to data transmission, lost or erroneous packets cannot be re-transmitted due to time constraints, but are simply omitted. Thus the degradation of the content, e.g., sound or image, must be evaluated.
Available assessment tools typically monitor and analyse network-level VoIP performance in terms of quality of service (=QoS) or compliance with service level agreements (=SLAs), using packet-based measurements such as jitter, loss, and delay (VoIP=Voice over Internet Protocol).
US 2004/0062204 A1 gives a short overview of conventional monitoring systems used for end-to-end measurements, i.e., from one terminal to another terminal. Some quality monitoring systems known on the market make use of so-called “synthetic” IP telephones, others utilise a so-called “passive” approach (IP=Internet Protocol). All prior art systems have considerable drawbacks which make it difficult to efficiently measure the contribution of a packet network to a streamed media quality degradation.